Apparatus, method and system for teaching elapsed time

ABSTRACT

A teaching clock for teaching the concept of elapsed time includes a clock face having a minute hand and an hour hand pivotally mounted to the clock face and an elapsed time indicator having an hour hand and a minute hand that move synchronously with the movement of the clock hands. The hour hand is connected to the minute hand such that pivotal movement of the minute hand about the clock face causes the hour hand to pivot synchronously therewith to designate a progression of hours of the day. The minute hand and hour hand are selectively positionable to display a time of day. The elapsed time display may include a releasable connection connected to the minute hand such that the elapsed time display resets to an initial or zero position upon release of the releasable connection whereby an elapsed time is shown by the elapsed time display between any two selected times of day shown by the minute hand and hour hand on the clock face.

This application is a continuation of U.S. Ser. No. 10/845,432 filed onMay 13, 2004, the entire contents of which are incorporated herein byreference.

BACKGROUND

The present application relates to teaching methods and associatedapparatus and systems and, more particularly, to methods, apparatus andsystems for teaching the concept of elapsed time.

The concept of elapsed time, that is, the number of hours and minutesbetween two times of day, is often difficult to teach to children. Thisconcept may be especially difficult when a child uses an analog clock.In order to teach this concept, teachers often employ teaching aids inthe form of teaching clocks. Such teaching clocks have the hour hand,minute hand and face with numbered hours of a conventional analog clock,but not the clockwork mechanism to move the hands. Typically, a teacherpositions the hands of such a teaching clock at a first selected time ofday, which is noted by students. The teacher then positions the hands ofthe teaching clock at a second selected time of day and the students areasked to determine the time interval between the first and second times.

An example of such a system is disclosed in U.S. Pat. No. 5,863,205.While that teaching clock has interconnected minute and hour hands thatare positionable, as well as a corresponding digital display of the sametime of day indicated by the hands, it lacks a mechanism for displayingthe time interval between two selected times of day.

Accordingly, there is a need for an apparatus, method and system forteaching students the concept of elapsed time and a method fordetermining the time that has elapsed between two times of day. There isalso a need for an apparatus, method and system for teaching studentshow to calculate ending time—the time of day after a given elapsed timefrom a given starting time, and beginning time—the time of day fromwhich a given elapsed time results in a given ending time.

SUMMARY

In one aspect, the disclosed apparatus for teaching elapsed time mayinclude a clock face on which are mounted a minute hand and an hour handinterconnected by a clock gear train such that pivotal movement of theminute hand about the clock face causes the hour hand to pivot so thatthe hands progress through the hours of the day indicated on the clockface. Consequently, the minute and hour hands are positionable todisplay a selected time of day.

The teaching clock may also include an elapsed time display, which inone embodiment includes smaller hour and minute hands, each on its owndial marked with hours and minutes, respectively. The elapsed timedisplay is releasably connected to the clock gear train such that theelapsed time display resets to an initial or zero position (for example,such that the hour and minute hands point to “12” and “60” on theirrespective faces) upon release of the releasable connection. In order toshow an elapsed time between any two selected times of day shown on theclock face, the clock hands first are set to a selected start orbeginning time. The releasable connection may be released, therebyzeroing the elapsed time display, such that the elapsed time displayresets to an initial or zero position while the minute hand and the hourhand show the start time. The minute hand and hour hand may then beadjusted to show a second, later time of day. As the minute and hourhands are pivoted to the second selected time of day, the minute andhour hands of the elapsed time display pivot to show the elapsed time ortime interval between the start time and the second, later time of day.

In another aspect, the disclosed system for teaching elapsed time mayinclude the teacher clock described above and a student clock. Thestudent clock may include a clock face having a minute hand and an hourhand pivotally mounted to the clock face. The hour hand may be connectedto the minute hand by a gear train such that pivotal movement of theminute hand about the clock face causes the hour hand to pivotsynchronously therewith to designate a progression of hours such thatthe minute hand and the hour hand are selectively positionable todisplay a time of day. The student clock may further include an elapsedtime display consisting of independently adjustable hour and minutehands pivotally mounted on separate faces marked with hours and minutes,respectively. The elapsed time display of the student clock may also beindependent of the clock minute and hour hands.

Thus, the hands of the teacher clock may be adjusted to show a firstselected time of day, the elapsed time display may be reset to a initialposition and a student may be instructed to set the hands of the studentclock to show a second, later time of day. The student may thendetermine the elapsed time and display it on the elapsed time display ofthe student clock by positioning the hands of the elapsed time display.A verification of elapsed time may then be obtained by adjusting theminute hand and hour hand of the teacher clock to correspond to thesecond selected time of day. This adjustment may automatically move thehands of the elapsed time display to show the correct elapsed time.Ending time may be taught by positioning the hands of the teacher clockat a beginning time, zeroing the elapsed time display and asking thestudent to determine (or show on the student clock) the ending time fora given elapsed time. The hands of the teacher clock may then be movedclockwise until the hands of the elapsed time display show the givenelapsed time. The ending time may then be indicated by hands of theteacher clock. Similarly, beginning time is taught by positioning thehands of the teacher clock at a predetermined ending time of day,zeroing the elapsed time display and asking the student to determine (orshow on the student clock) the beginning time for a given elapsed time.The hands of the teacher clock may then be moved counterclockwise untilthe hands of the elapsed time display show the given elapsed time(measured counterclockwise).

Other aspects of the disclosed apparatus, method and system for teachingelapsed time will become apparent from the following description, theaccompanying drawings and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front elevational view of the face a teacher clock of thepresent invention;

FIG. 2 is an exploded, perspective view of the teacher clock of FIG. 1;

FIG. 3 is a front elevational view of the face of a student clock of thepresent invention;

FIG. 4 is an exploded, perspective view of the student clock of FIG. 3;

FIG. 5 is a front elevational view of the face of the teacher clock ofFIG. 1 displaying a second selected time of day and the correct elapsedtime from the time shown on the face in FIG. 1;

FIG. 6 is a front elevational view of the face of the teacher clock ofFIG. 1 displaying a third selected time of day and the correct elapsedtime from the time shown on the face in FIG. 1;

FIG. 7 is a front elevational view of the face of the student clock ofFIG. 3 displaying a second selected time of day and the elapsed timefrom the time shown on the face in FIG. 3; and

FIG. 8 is a front elevational view of the face of the student clock ofFIG. 3 displaying a third selected time of day and the elapsed time fromthe time shown on the face in FIG. 3.

DETAILED DESCRIPTION

One aspect of the disclosed teacher clock, generally designated 10, mayinclude a clock face 12 having an outer shell 12A with a minute hand 14and an hour hand 16 pivotally mounted thereto. The hour hand 16 may beconnected to the minute hand 14 by a gear train 30 (see FIG. 2) suchthat a manual movement of the minute hand 14 about the clock face 12causes synchronous and corresponding movement of the hour hand 16 todesignate a time of day.

Numerical indicia representing the hour component 15 and minutecomponent 15A of the time of day may be displayed around the peripheryof the clock face 12. Specifically, the numbers 1 through 12 may bepositioned and equally spaced around the periphery of the clock face 12to indicate the hour component 15 and the numbers 5, 10, 15, 20, 25, 30,35 40, 45, 50, 55 and 60 may also be positioned around the periphery ofthe clock face 12 to indicate the minute component 15A.

The clock face 12 may also include an elapsed time display 17 thatincludes an hour indicating face 17A with an analog hour indicator 18and a minute indicating face 17B with an analog minute indicator 20. Theanalog hour indicator 18 may include an elapsed time hour hand 19pivotally mounted thereto and hour-indicating indicia 21 disposed aboutthe periphery of the analog hour indicator. Similarly, the analog minuteindicator 20 may include an elapsed time minute hand 22 pivotallymounted thereto and minute indicating indicia 23 disposed about theperiphery of the analog minute indicator. As will be described withreference to FIG. 2, the analog hour indicator 18 and analog minuteindicator 20 may be releaseably connected to the minute hand 14 and hourhand 16 such that movement of the minute hand 14 about the clock face12, and corresponding movement of the hour hand 16, moves the elapsedtime minute hand 22 and the elapsed time hour hand 19 a correspondingamount. Those skilled in the art will appreciate that the elapsed timedisplay 17 may be a digital elapsed time display.

As shown in FIG. 2, the teacher clock 10 may include a gear train 30enclosed within the outer shell 12A and inner shell 12B of face 12. Thegear train 30 may include six spur gear elements that interconnect theminute hand 14, the hour hand 16, the elapsed time minute hand 22 andthe elapsed time hour hand 19. The gear train 30 may include a firstgear element 32, second gear element 34, third gear element 36, fourthgear element 42, fifth gear element 44 and sixth gear element 50.

The first, second and third gear elements 32, 34, 36 may connect theminute hand 14 to the hour hand 16 for synchronous movement. The firstgear element 32 may include a shaft 33, a small diameter spur gear 32Aand a large diameter spur gear 32B. An adjustment knob 40 may beattached to an inner end of shaft 33 of first gear element 32. Thesecond gear element 34 may include a hollow shaft 35 and one largediameter spur gear 34B. The third gear element 36 may include a smalldiameter spur gear 36A and a large diameter spur gear 36B and may berotatably mounted on post 36C. Spur gears 32A and 36A may have the samepitch diameters. Spur gears 34B and 36B may have the same pitchdiameters, which may be twelve times greater than the pitch diameters ofspur gears 32A and 36A. For example, if spur gears 32A and 36A each hada pitch diameter of 5 mm, spur gears 34B and 36B each would have a pitchdiameter of 60 mm.

The shaft 33 of the first gear element 32 may be coaxially receivedwithin the hollow shaft 35 of the second gear element 34 such that bothshafts 33, 35 extend through an opening 39 through the clock face 12.The minute hand 14 may be connected to the outer end of shaft 33 of thefirst gear element 32 that protrudes through opening 39 and the hourhand 16 may be connected to an outer end of the hollow shaft 35 of thesecond gear element 34 that protrudes through an opening 39 in the outershell 12A. The first gear element 32 may be connected to the second gearelement 34 by the third gear element 36. Spur gear 32A may be connectedto spur gear 36B and spur gear 36A may be connected to spur gear 34B.Therefore, one full (i.e., 360°) rotation of the first gear element 32may correspond to one-twelfth of a rotation (i.e., 30°) of the thirdgear element 36, which may correspond to one-twelfth of a rotation(i.e., 30°) of the second gear element 34, such that one full rotationof the minute hand 14 about the clock face 12 may correspond toone-twelfth of a rotation of the hour hand 16 about the clock face 12.

The fourth and fifth gear elements 42, 44 may be responsible forsynchronously connecting the elapsed time minute hand 22 of the analogminute indicator 20 to the movement of the minute hand 14 and hour hand16. The fourth gear element 42 may include a shaft 43 and a largediameter spur gear 42B. The fifth gear element 44 may be rotatablymounted on post 44A and may include a large diameter spur gear 44B. Spurgears 42B and 44B may each have the same pitch diameter as spur gear32B.

The elapsed time minute hand 22 may rotate about the analog minuteindicator 20 (see FIG. 1) synchronously with the minute hand 14. Theelapsed time minute hand 22 may be connected to the shaft 43 of thefourth gear element 42. Rotation of the first gear element 32 (which maybe accomplished by manual rotation of knob 40 or manual rotation ofminute hand 14) may be translated into corresponding rotation of thefourth gear element 42. Spur gear 32B may be connected to spur gear 44B,which in turn may be connected to spur gear 42B. For example, if spurgear 32B is rotated clockwise relative to the clock face 12, then spurgear 44B would rotate counterclockwise and spur gear 42B would rotateclockwise.

The sixth gear element 50 may connect the elapsed time hour hand 19 ofthe analog hour indicator 18 to move synchronously with the minute hand14 and hour hand 16. The sixth gear element 50 may include a shaft 51connected to the elapsed time hour hand 19 and a large diameter spurgear 50B that has the same pitch diameter as spur gear 36B. Spur gear50B may be connected to spur gear 36B such that rotation of the firstgear element 32 by knob 40 rotates the elapsed time hour hand 19, whichcorresponds to the movement of the hour hand 14.

Releasing the releasable connection between the elapsed time display 17and the minute hand 14 and hour hand 16 such that the elapsed time hourhand 19 and elapsed time minute hand 22 may be biased to an initialposition may reset the elapsed time display 17. The elapsed time hourhand 19 and elapsed time minute hand 22 may be biased to an initial orzero position by a spring 60. For example, the spring 60 may bias theelapsed time hour hand 19 to the “12 o'clock” position and the elapsedtime minute hand 22 to the “60 minute” position as shown in FIG. 1.

The elapsed time hour hand 19 may be reset to an initial position byreleasing the releasable connection between the sixth gear element 50and the third gear element 36. The connection may be released by freeingthe teeth of spur gear 50B from meshing engagement with the teeth ofspur gear 36B by axial movement of gear element 50, thereby allowing thespring 60 to rotate the gear element 50 and corresponding elapsed timehour hand 19 to the initial position.

Similarly, the elapsed time minute hand 22 may be reset to an initialposition by releasing the releasable connection between gear element 42and gear element 44. The connection may be released by freeing the teethof spur gear 42B from the teeth of spur gear 44B by axial movement ofgear 42, thereby allowing the spring 60 to rotate the fourth gearelement 42 and corresponding elapsed time minute hand 22 to the initialposition.

A knob and bar assembly may be used to simplify releasing the releasableconnections to reset the elapsed time display 17. As shown in FIG. 2,the bar and knob assembly may include two knobs 62, 64, slidablyreceived in slotted sleeves 62B, 64B mounted on the inner face of shell12A. The assembly may also include two bars 63, 65 that are slidablymounted on studs 63A, 65A and which may be held into position and biasedtowards the inner face of shell 12A by springs 63C, 65C that are mountedon studs 63D, 65D, respectively. Knob 62 and bar 63 may be aligned suchthat when knob 62 is depressed against the bias of spring 66, tab 62Athereof urges bar 63 in an axial direction against gear element 42,thereby urging spur gear 42B axially out of engagement with spur gear44B to release the releasable connection therebetween. Further, knob 64and bar 65 may be aligned such that when knob 64 is depressed againstthe bias of spring 67, tab 64A thereof urges bar 65 against gear element50, thereby urging spur gear 50B axially out of engagement with spurgear 36B to release the releasable connection therebetween.

For convenience, the teacher clock 10 may include a handle assembly 70to make it easier to carry. Further, a slot 72, shaped to receive thehead of a screw or nail, may be provided so that the teaching clock 10may be hung from a wall or the like. Still further, a stand 74 may bepivotally attached to the back of the teacher clock 10 and retainedwithin a recess 75 to allow the clock 10 to stand on a table or othersurface. Additionally, a knob 40 may be directly connected to the firstgear element 32 to simplify rotation of the first gear element 32 andcorresponding movement of the minute hand 14, hour hand 16 and elapsedtime display 17.

As shown in FIG. 3, a student clock, generally designated 100, mayinclude a clock face 112 with inner and outer clock face shells 112 A,112B (see also FIG. 4) with a minute hand 104 and an hour hand 106pivotally mounted thereto. The hour hand 106 may be connected to theminute hand 104 by a gear train 125 (see FIG. 4) such that movement ofthe minute hand 104 about the clock face causes synchronous andcorresponding movement of the hour hand 106 to designate a time of day.

Various numeric indicia 115 may be displayed around the periphery of theclock face 112. The numbers 1 through 12 may be positioned and equallyspaced around the periphery of the clock face 112 to indicate an hourcomponent of the time of day. Furthermore, the indicia 115 may includethe numbers 5, 10, 15, 20, 25, 30, 35 40, 45, 50, 55 and 60 positionedaround the periphery of the clock face to indicate a minute component ofthe time of day.

The student clock face 112 may also include an elapsed time display 117having an analog hour indicator 118 and an analog minute indicator 120positioned on the clock face. The analog hour indicator 118 may includean elapsed time hour hand 119 pivotally mounted thereto and hourindicating indicia 121 disposed about the periphery of the analog hourindicator 118. The analog minute indicator 120 may include an elapsedtime minute hand 122 pivotally mounted thereto and minute indicatingindicia disposed about the periphery of the analog minute indicator 120.The elapsed time hour hand 119 may engage detent arm 119A, which mayengage detents formed on the inner surface of indicator 118, and tubularknob 119B that extends through the inner shell 112B to facilitate manualrotation of the elapsed time hour hand. Similarly, elapsed time minutehand 122 may engage detent arm 122A, which may engage detents formed onthe inner surface of indicator 120, and tubular knob 122B that extendsthrough the inner shell 112B to facilitate manual rotation of theelapsed time minute hand. In contrast to the teacher clock 10 (FIGS. 1,2and 5), the analog hour indicator 118 and analog minute indicator 120 ofthe student clock 100 may pivot independently of each other and of theminute hand 104 and hour hand 106. In an alternative aspect, the elapsedtime display 117 may be a digital elapsed time display.

As shown in FIG. 4, the gear train 125 may be contained between theinner and outer shells 112A, 112B and may include three spur gears thatinterconnect the minute hand 104 and the hour hand 106. The gearassembly 125 may include a first gear element 130, a second gear element135 and a third gear element 140.

The first gear element 130 may include a shaft 131 and a small diameterspur gear 130A. The second gear element 135 may include a hollow shaft136 and one large diameter spur gear 135B. The third gear element 140may include a small diameter spur gear 140A and a large diameter spurgear 140B. Spur gears 130A and 140A may have the same pitch diameter.Spur gears 135B and 140B may have the same pitch diameter, which may betwelve times larger than that of spur gears 130A and 140A. For example,if spur gears 130A and 140A each were to have a pitch diameter of 5 mm,spur gears 135B and 140B would each have a pitch diameter of 60 mm.

The shaft 131 of the first gear element 130 may be coaxially receivedwithin the hollow shaft 136 of the second gear element 135 such thatboth shafts 131, 136 extend through an opening 150 through the clockface 112. The end of the shaft 131 of the gear element 130 opposite theshell 112A may extend through the inner shell 112B and receives a knob130B to facilitate manual rotation of the shaft. The minute hand 104 maybe connected to the shaft 131 of the first gear element 130 and the hourhand 106 may be connected to the hollow shaft 136 of the second gearelement 135. The first gear element 130 may be connected to the secondgear element 135 by the third gear element 140, which may be rotatablymounted on post 140C. Spur gear 130A may mesh with spur gear 140B andspur gear 140A may mesh with spur gear 135B. Therefore, one full (i.e.,360°) rotation of the first gear element 130 (as by manual rotation ofknob 130B) may correspond to one-twelfth of a rotation (i.e., 30°) ofthe third gear element 140, which may correspond to one-twelfth of arotation (i.e., 30°) of the second gear element 135, such that one fullrotation of the minute hand 104 about the clock face 112 corresponds toone-twelfth of a rotation of the hour hand 106 about the clock face.

Thus, the concepts of elapsed time, beginning time and ending time maybe taught using both the teacher clock 10 and the student clock 100, oralternatively, only the teacher clock. As shown in FIG. 1, to teach theconcept of elapsed time, the minute hand 14 and hour hand 16 of theteacher clock 10 may first be set to an initial time of day (forexample, 6:00, as shown in FIG. 1) and the elapsed time display 17A, 17Bzeroed in the manner described above. The minute hand 104 and hour hand106 of the student clock 100 may be set to a second time of day (forexample, 7:30, as shown in FIG. 7). The student may then be asked todetermine the amount of time that has elapsed between the first time ofday (i.e., 6:30) shown on the teacher clock 10 and the second time ofday (i.e., 7:30) shown on the student clock 100. Once the student hasdetermined the elapsed time (i.e., 1 hour and 30 minutes), the studentmay manually display the determined elapsed time using the elapsed timedisplay 117A, 117B of the student clock 100 by pivoting the elapsed timehour hand 119 to display 1 hour and the elapsed time minute hand 122 todisplay 30 minutes. Alternatively, the student may write down or statethe elapsed time. As shown in FIG. 5, to verify that the student hasdetermined the correct elapsed time, the teacher may move the minutehand 14 and hour hand 16 clockwise to the second time of day (i.e.,7:30), wherein the elapsed time display 17A, 17B would display thecorrect elapsed time (i.e., 1 hour and 30 minutes) automatically.

Similarly, the concept of ending time may be taught by positioning thehands 14, 16 of the teacher clock 10 at a selected beginning time, forexample, 6:00, as shown in FIG. 1. The elapsed time display 17A, 17B maybe zeroed and the student may be asked to show on the student clock 100(or, alternatively, to write down or to state verbally) the ending timefor a given elapsed time, for example 1 hour and 30 minutes. As shown inFIG. 7, the student may position the hands 104, 106 of the student clock100 to 7:30. Optionally, the student may also position the hands 119,122 of the elapsed time display 117A, 117B to show the desired elapsedtime, either before determining the ending time or afterward. As shownin FIG. 5, in order to verify the student's answer, the hands 14, 16 ofthe teacher clock 10 may then be moved clockwise until the hands 19, 22of the elapsed time display 17A, 17B show the desired elapsed time (1hour and 30 minutes). The ending time (7:30) may then be indicatedautomatically by the hands 14, 16 of the teacher clock 10.

The concept of beginning time may be taught by positioning the hands 14,16 of the teacher clock 10 at a predetermined ending time of day, forexample 6:00 as shown in FIG. 1, and zeroing the elapsed time display17A, 17B. The student may then be asked to show on the student clock 100(or, alternately, to write down or to say verbally) the beginning timefrom which a given elapsed time, for example 1 hour and 30 minutes,would result in the ending time of 6:00. As shown in FIG. 8, the studentwould respond by setting the hands 104, 105 of the student clock 100 atthe correct beginning time (4:30) from which the desired elapsed time of1 hour and 30 minutes would result in the desired ending time of 6:00.Optionally, the student may also set the hands 119, 122 to indicate thegiven elapsed time. As shown in FIG. 6, to verify the student's answer,the hands 14, 16 of the teacher clock 10 may then be movedcounterclockwise until the hands 19, 22 of the elapsed time display 17A,17B show the desired elapsed time of 1 hour and 30 minutes (measuredcounterclockwise from the “12” and “60” positions, respectively). Thehands 14, 16 will, at that point, automatically indicate the correctbeginning time of 4:30.

Although various aspects of the disclosed apparatus, method and systemfor teaching elapsed time have been shown and described, modificationsmay occur to those skilled in the art upon reading the specification.The present application includes such modifications and is limited onlyby the scope of the claims.

1. A system for teaching elapsed time comprising: a teacher clockincluding: a clock face; a minute hand pivotally mounted to said clockface; an hour hand pivotally mounted to said clock face and connected tosaid minute hand such that pivotal movement of said minute hand aboutsaid clock face causes said hour hand to pivot synchronously therewithto designate a progression of hours, whereby said minute hand and saidhour hand are selectively positionable to display a time of day; and anelapsed time display having a releasable connection connected to saidminute hand, such that said elapsed time display resets to an initialposition upon release of said releasable connection, whereby an elapsedtime is shown by said elapsed time display as a result of movement ofsaid minute hand and said hour hand between any two selected times ofday on said clock face; a student clock including: a clock face; aminute hand pivotally mounted to said clock face; an hour hand pivotallymounted to said clock face and connected to said minute hand such thatpivotal movement of said minute hand about said clock face causes saidhour hand to pivot synchronously therewith to designate a progression ofhours, whereby said minute hand and said hour hand are selectivelypositionable to display a time of day; and an elapsed time displayadjustable independently of said student clock minute hand; wherein saidminute hand and said hour hand of said teacher clock are adjusted toshow a first selected time of day and said elapsed time display isreset, and said minute hand and said hour hand of said student clock areadjusted to show a second selected time of day, such that a student maydetermine an elapsed time between said first selected time of day andsaid second selected time of day and display said determined elapsedtime on said elapsed time display on said student clock; and wherein averification elapsed time is obtained by adjusting said minute hand andsaid hour hand on said teacher clock to correspond with said secondselected time of day such that said elapsed time display on said teacherclock displays said verification elapsed time.
 2. The system of claim 1wherein said clock face of said teacher clock includes numeric indiciapositioned along a periphery of said clock face.
 3. The system of claim1 wherein said elapsed time display of said teacher clock includes ananalog minute display and an analog hour display.
 4. The system of claim1 wherein said elapsed time display of said teacher clock includes aface displaying hours and a face displaying minutes.
 5. The system ofclaim 1 wherein said clock face of said student clock includes numericindicia positioned along a periphery of said clock face.
 6. The systemof claim 1 wherein said elapsed time display of said student clockincludes an analog minute display and an analog hour display.
 7. Thesystem of claim 1 wherein said elapsed time display of said studentclock includes a digital minute display and a digital hour display.
 8. Amethod for teaching the concept of ending time to a student comprisingthe steps of: providing a clock face having a minute hand and an hourhand pivotally mounted thereto, said hour hand being connected to saidminute hand such that pivotal movement of said minute hand about saidclock face causes said hour hand to pivot synchronously therewith todesignate a progression of hours, whereby said minute hand and said hourhand are selectively positionable to display a time of day; providing anelapsed time display having a releasable connection connected to saidminute hand; pivoting said minute hand clockwise about said clock faceto position said minute hand and said hour hand to display a selectedbeginning time of day; actuating said releasable connection such thatsaid elapsed time display resets to an initial position corresponding tosaid beginning time of day; selecting a desired elapsed time; asking astudent to calculate an ending time resulting from said desired elapsedtime added to said beginning time of day; verifying a result reached bysaid student by pivoting said minute hand and said hour hand from saidbeginning time of day to an ending time of day at which said elapsedtime display has moved from said initial position to indicate saiddesired elapsed time; and comparing said ending time of day with saidcalculated ending time.
 9. The method of claim 8 wherein said askingstep includes the step of asking said student to display said calculatedending time on a student clock.
 10. A method for teaching the concept ofelapsed time to a student comprising the steps of: providing a clockface having a minute hand and an hour hand pivotally mounted thereto,said hour hand being connected to said minute hand such that pivotalmovement of said minute hand about said clock face causes said hour handto pivot synchronously therewith to designate a progression of hours,whereby said minute hand and said hour hand are selectively positionableto display a time of day; providing an elapsed time display having areleasable connection connected to said minute hand; pivoting saidminute hand clockwise about said clock face to position said minute handand said hour hand to display a selected beginning time of day;actuating said releasable connection such that said elapsed time displayresets to an initial position corresponding to said beginning time ofday; selecting a desired ending time of day; asking a student tocalculate an elapsed time between said beginning time of day and saidending time of day; verifying a result reached by said student bypivoting said minute hand and said hour hand from said beginning time ofday to said ending time of day at which said elapsed time display hasmoved from said initial position to indicate said elapsed time; andcomparing said indicated elapsed time with said calculated elapsed time.11. The method of claim 10 wherein said asking step includes the step ofasking said student to display said calculated elapsed time on anelapsed time display of a student clock.